I'm totaly lost trying to make sense of sub calibration.Using the auto on my Boston 120 the settings are right on with Sound and Vision's test disc using the rat shack spl.However the reciever always maxxes the sub to +15 no matter the gain-EP350.One article says set the reciever to -10,another to +10????????? then use the spl.My understanding is 0 on the recievers level settings is actually adjusted to -10 or not?????.The recievers test tone maxxes the needle no matter the sub gain setting,however using S+V calibration disk for subs,left main-sub,I can set them both to 75db but the 350 is set in the area of 6:30-7:00. I've been browsing the web and its all mumbo-jumbo and conflicting opinions so I am hoping a fellow 350 owner can offer some advice,Thanks.

King, some of the points you described were unclear. If you mean that the 120's auto calibration boosted the sub trim up to +15dB(the maximum?), the indication would be that the level control on the sub itself was set too low for the calibration and should be set higher so that the receiver sub trim will come out lower than +15 to compensate. But do you mean that even if you calibrate with the sub control all the way up that the receiver still sets the trim at +15dB?

I also don't follow the -10, +10 and spl comment. Can you clarify some of this a bit more?

It seems no matter where I set the level on the 350 the auto setup always sets the sub to +15,I can set it at 9:00 or max it out and it will always set it to +15,I'm not sure but I seem to recall someone else here saying there Denon I believe did the same thing.Afterwards if I go into the speaker trim settings it will show the settings as something like f=0,ctr-2,fr+1,sr+2,sl+3,sw0 ???.By the -10,+10 all I meant was in the articles I read that was a example of how wide a difference different "experts" say to set the trim.That is part of my confusion,the wide difference of opinion on how to calibrate a sub.Do I run the auto set up and then use the test disc lf-sub to set the level ? I am assuming the reciever is bumping the level to whatever and showing that in the trim settings as a reference point ??? I know if I go into the subwoofer trim menu it will show the setting as 0,but it will also show in the same menu the DTS setting as +15.I might be over analyzing but I just thought I'd try to match everything out right and take it from there.Just for yuks I googled subwoofer calibration and was surprised at just how wide a difference of opinion there is.That was the basis of this post.A little more info here,I started out with the 350 at about 10:30 or so and it was fine untill you start getting loud then everything in the house not nailed down vibrates.Maybe a low 7:00 trim is right ? My setup is in a appr.15-22 room that is basicly a concrete bunker and I always have gotten good bass.I started out with just a small 50 watt Yamaha from a htb and it was fine at about 2/3 power.I moved up to a huge Velodyne and 1/6 was plenty.I am just totaly lost trying to do my 350,hope the additional info helps.Al

Ar har! It is possible that auto setup is just setting the Dolby Digital settings, and not the DTS settings. I know that my H/K keeps those separate (although I don't have true auto separate) and I have to calibrate them separately.

You could try moving your mic a little when doing the auto calibration. It could be in a dead spot where all the bass cancels out and the mic doesn't actually hear it at all, even though your walls are shaking apart. So the receiver just keeps cranking up the gain hoping to hear it eventually but never does, so it just leaves it maxed out. Just an idea you can try out.

I have found every auto-calibration function to be not very useful for the simple reason that a receiver would need far more processing power than available to take accurate measurements and factor in unique room acoustics. Last year I had a long conversation with Anthem engineers regarding why they were not offering auto-equalization in their flagship processor. It was also their belief that they would need to have a very powerful CPU to get it right. I see the same issue with the auto-calibration function in my SMS-1. Bottom line, don't rely on auto-calibration--it is there for marketing purposes and usually gives inaccurate results.

You will get far better results doing it manually using the calibration tones, reading the SPL metre, measuring distance for delay and making small placement adjustments. My suggestions:

1. Turn off auto-calibration.

2. Calibrate all your speakers first to 75db.

3. Measure distance then set delay for each of them. You may want to set the surround speakers to slightly more delay for effect.

4. Turn off sound to all speakers.

5. Set the subwoofer volume to -7 (a quarter of the way down to leave you some room for fine tuning).

6. Run the LF sweep on S & V and adjust gain at the sub so the needle spends most of its time at 75db at your favourite seating position.

7. Go and move the sub around to see if you can get less flucuation on the SPL metre at 75db.

8. Play sound through the mains and sub.

9. Flick the phase switch to see whether 0 or 180deg has more SPL at the seating position. Leave the phase at the higher setting.

10. Measure the distance to the sub and input the delay setting for the receiver. Many subs benefit from increasing delay another 3-5 feet than the measured distance depending on room acoustics, so experiment.

10. Test with your favourite music or movie. I you want more bass increase your receiver setting not the gain at the sub.

When I owned my 350 using my current Denon 2805, the only strange that was a result of the auto setup is that the Denon put the delay (distance) for the 350 around 28ft, even though it was more like 14ft. After reviewing the manual, from JohnK's input, it clearly stated this was normal based on the internal circuitry of some subs.

Your situation seems different, my 350 volume (gain) was usually around 11-12 o'clock to start, crossover turned all the way clockwise (bypass) since I was using the receivers crossover of 80hz. After setup, the receiver levels for the sub was around -2dB. With my EP500 it is at -4dB, with the gain set very low.

I am not familiar with your receiver/amp, so can't help much, but does not seem normal to me. I like Jakeman's steps above, may have to give them a try myself...

Thanks all for the replys.Jakeman,I will try that tonight.Auto setup on the Boston actualy comes out right where it does on manual but I will try the level with the disc and sub only,sounds like a good idea.There is no sub delay-distance setting I can find,hmmm,only speakers?.I ran it again this am and it matches what I came up with using the test disc,then in the trim menu it shows them all set as 0.I do then bump up the surrounds +1 just for personal prefference.Hmmm,it just seems no matter where I set the 350 at using the reciever test tone peggs out the spl meter?.Guess I have to use S&V to get any kind of accurate reading.I know I had it set to high from the begining,maybe around 7:00 is right.You and Sirquack have given me something to work with.Like I posted earlier I was lost,expert A says set rec.gain at -10 and calibrate,expert B says +10 and calibrate,expert C says both are the same????? ARGH!! but set at +4 should have just started with my fellow ownwers here and saved myself the agravation.Just thought it might be a quirk of the Boston 120-Sherwood r-965.Al

With regards to your starting point the reason I suggested calibrating your speakers first is because by doing so you will have the main receiver volume already set before starting the sub calibration. Leave the main volume to where you have adjusted your speakers to 75db.